1. Field of the Invention
The present invention relates to a novel fatty acid cholesterol ester and a cosmetic composition containing the same.
2. Description of the Prior Art
Cholesterol is widely distributed in nature, and especially in the animal body, it is distributed in almost all systems including brain cells and is believed to play a very important role in physiological processes. It is industrially used as a raw material for the synthesis of pharmaceuticals, as an additive for cosmetics and as a raw material for liquid crystals.
While it is clear that cholesterol is useful by itself, as mentioned above, there have been various attempts to reform cholesterol by subjecting it to various reactions to obtain its derivitives having novel properties which are not seen in cholesterol, per se.
Cholesterol has a unique sterol structure with a hydroxyl group at the C.sub.3 position and an in-ring double bond at the C.sub.5 -C.sub.6 position. It is conceivable that a chemical reaction suitable for an alcohol may be applied to the hydroxyl group at the C.sub.3 position. For instance, various cholesterol esters obtainable by esterification of fatty acids and cholesterol, are known to be widely used, e.g., in the liquid crystal field (Japanese Patent Publication No. 11143 of 1970), as an intermediate for the synthesis of a steroid hormone (Japanese Patent Publication No. 40799 of 1972) and for a carcinostatic substance (Japanese laid-open patent application No. 25117 of 1974). Further, it is known that an addition product obtainable by the addition of an alkylene oxide such as ethylene oxide or propylene oxide to cholesterol, has an improved hydrophilic property over cholesterol by virtue of the addition of the alkylene oxide, and thus has an improved emulsion stability, and it is useful as a base material for a cosmetic and as an emulsifier (Japanese patent publication No. 28501 of 1975).
However, most of the above mentioned cholesterol derivatives have a high melting point and are normally solid at room temperature. Accordingly it is necessary to take special measures for their use, and in some cases, the amounts or the ranges of their use are limited. Some of them give irritation to the skin upon application and their use for cosmetics is accordingly limited.
A need therefore continues to exist for cholesterol based materials useful as emulsifiers which are liquid at room temperature and give little irritation to the skin.